code: def encode_pos(i, j):
      """Encodes a pair (i, j) as a scalar position on the board."""
      return 3 * i + j
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import gym
  from gym import spaces
  from gym.utils import seeding
  import numpy
  from tensor2tensor.data_generators import problem
  from tensor2tensor.layers import modalities
  from tensor2tensor.rl import gym_utils
label_desc: Use image node_id 1 for calling a global function with example usage: encode_pos(i, j) and returns: unknown